Featured Research

Influencing Structure In The Heart Of Nanoland: Light Used To Control Size Of Nanopores

Date:

October 6, 2000

Source:

Sandia National Laboratories

Summary:

Pianos and cars may be tuned with wrenches and screwdrivers, but the old clunky tools just won't do to adjust the sizes of trillions of nanoscopic pores in fine filters, sensors, or diffraction gratings to make them work better. Now, in the Oct. 6 issue of the journal Science, an Albuquerque-based research group reports precise size adjustments of nanopores through use of a simple ultraviolet beam of light.

Share This

ALBUQUERQUE, N.M. - Pianos and cars may be tuned with wrenches and screwdrivers, but the old clunky tools just won't do to adjust the sizes of trillions of nanoscopic pores in fine filters, sensors, or diffraction gratings to make them work better.

Related Articles

Now, in the Oct. 6 issue of the journal Science, an Albuquerque-based research group reports precise size adjustments of nanopores through use of a simple ultraviolet beam of light.

The precision is so great that it could achieve the long-sought goal of membrane-based separation of oxygen from nitrogen, a difference in size of 0.2 Angstroms [0.02 nanometers], says Jeff Brinker, senior scientist at the Department of Energy's Sandia National Laboratories, professor at the University of New Mexico, and lead researcher on the multi-institution project. A joint patent application has been filed on the process by Sandia and UNM.

"The Holy Grail of membrane science is air separation," says Brinker. "People would love a filter that could separate oxygen from nitrogen. Industrialists have invested hundreds of millions of dollars to do that. Now, in a systematic way, we might go from pores of, say, 3.4 to 3.6 angstroms in diameter, tuning the membrane to optimize oxygen-nitrogen separation."

The work is an extension of a four-paper series published by Brinker's group in the journal Nature, detailing the group's inquiries into the properties of nanostructures that self-assemble to produce repeating patterns of pores of exactly the same size.

In this case, the honeycomb-like structure, which might be visualized as a group of soda straws lying together in a bundle, have pores that shrink in unison when illuminated by a beam of light.

"Using light to change pore size is a kind of nanostructural engineering," Brinker says. "In addition to creating an overall pattern as achieved by conventional lithography, this kind of lithography also can help us define the internal structure of the films on the nanoscale. Even though the overall shapes we create are at the high end of the nanostructure regime, the light influences pore size and connectivity in the heart of nanoland, varying pore sizes continuously over a range within that illuminated pattern."

Creating tunable zeolitesIn effect, he says, the process creates a kind of tunable zeolite, thereby enhancing the capability of membranes to separate molecules by size. (Zeolites are crystalline structures with tiny but unalterable pore sizes widely used by industry to separate materials. As filters they are precise, but their pore sizes are unchangeable.)

This is done merely by exposing the membrane - in this case, self-assembled thin-film silica that is photosensitive - to the proper amount of light. "Tuning a ten-angstrom hole to 8 or 9 angstroms should make a huge difference in membrane performance," says Brinker.

Key to the pore size changes are photoacid molecules that self-assemble and uniformly incorporate into a periodic nanostructure. A light shone on these molecules breaks them apart to form an acid that causes silica to solidify locally. The amount of solidification, which necessarily shrinks pore sizes to create the denser material, is proportional to the amount of light shone on the membrane.

In the paper's introduction, the authors write, "The ability to optically define and continuously control both structure and function on the macro- and mesoscales is of interest for sensor arrays, nanoreactors, photonic and fluidic devices, and low-dielectric-constant films."

A further feature involves shining light through a lithographic mask that varies its intensity, producing so-called "gray-scale" patterning, which theoretically allows for a broad continuous spatial variation of the materials' structure and properties.

The same process also can be used to produce optical diffraction gratings - devices that can redirect and filter light - made entirely of laser-damage-resistant silica.

"While modifying pore sizes by small amounts so far seems to be completely controllable, we haven't yet demonstrated control in going from huge to teeny pores," says Brinker. "We're not sure what the dynamic range of the process is."

Other researchers on this project include Alan Hurd from Sandia and researchers from the Vienna University of Technology and Applied Materials Corp. in Santa Clara, Calif.

The work is funded by DOE's Office of Basic Energy Sciences, the Defense Advanced Research Projects Agency (DARPA), and Sandia's Laboratory-Directed Research and Development (LDRD) program.

Sandia is a multiprogram DOE laboratory, operated by a subsidiary of Lockheed Martin Corp. With main facilities in Albuquerque, N.M., and Livermore, Calif., Sandia has major research and development responsibilities in national security, energy, and environmental technologies.

Sandia National Laboratories. "Influencing Structure In The Heart Of Nanoland: Light Used To Control Size Of Nanopores." ScienceDaily. ScienceDaily, 6 October 2000. <www.sciencedaily.com/releases/2000/10/001006075356.htm>.

Sandia National Laboratories. (2000, October 6). Influencing Structure In The Heart Of Nanoland: Light Used To Control Size Of Nanopores. ScienceDaily. Retrieved March 3, 2015 from www.sciencedaily.com/releases/2000/10/001006075356.htm

Sandia National Laboratories. "Influencing Structure In The Heart Of Nanoland: Light Used To Control Size Of Nanopores." ScienceDaily. www.sciencedaily.com/releases/2000/10/001006075356.htm (accessed March 3, 2015).

More From ScienceDaily

More Matter & Energy News

Featured Research

Mar. 3, 2015 — By examining the forces that the segments of mosquito legs generate against a water surface, researchers have unraveled the mechanical logic that allows the mosquitoes to walk on water, which may ... full story

Mar. 3, 2015 — Researchers have developed a new way of rapidly screening yeasts that could help produce more sustainable biofuels. The new technique could also be a boon in the search for new ways of deriving ... full story

Mar. 3, 2015 — Major cities in the UK are falling behind their international counterparts in terms of their use of smart technologies, according to a new study. The research has found that smart cities in the UK, ... full story

Mar. 3, 2015 — Scientists have explored friction at the microscopic level. They discovered that the force generating friction is much stronger than previously thought. The discovery is an important step toward ... full story

Mar. 3, 2015 — Micro-drones are already being put to use in a large number of areas: These small aircraft face extensive requirements when performing aerial observation tasks or when deployed in the field of ... full story

Mar. 3, 2015 — Recent research contributes to the effort to determine the nature of dark matter, one of the most important mysteries in physics. As indirect evidence provided by its gravitational effects, dark ... full story

Mar. 3, 2015 — Physicists have shown for the first time that electrons in graphene can be moved along a predefined path. This movement occurs entirely without loss and could provide a basis for numerous ... full story

Mar. 3, 2015 — Magnetic vortex structures, so-called skyrmions, could in future store and process information very efficiently. They could also be the basis for high-frequency components. For the first time, a team ... full story

Featured Videos

Forensic Holodeck Creates 3D Crime Scenes

Reuters - Innovations Video Online (Mar. 3, 2015) — A holodeck is no longer the preserve of TV sci-fi classic Star Trek, thanks to researchers from the Institute of Forensic Medicine Zurich, who have created what they say is the first system in the world to visualise the 3D data of forensic scans. Jim Drury saw it in operation.
Video provided by Reuters

Solar Plane Passes New Test Ahead of World Tour

AFP (Mar. 2, 2015) — A solar-powered plane made a third successful test flight in the United Arab Emirates on Monday ahead of a planned round-the-world tour to promote alternative energy. Duration: 01:05
Video provided by AFP

Electric Hydrofoiling Watercraft Delivers Eco-Friendly Thrills

Reuters - Innovations Video Online (Mar. 2, 2015) — The Quadrofoil is a high-tech electric personal watercraft that its makers call a &apos;sports car for the water&apos;. When it hits 10 km/h, the Slovenian-engineered Quadrofoil is lifted above the water onto four wing-like hydrofoils where it &apos;flies&apos; above the surface with minimal water resistance. Matthew Stock reports.
Video provided by Reuters

Related Stories

May 20, 2013 — The allure of personalized medicine has made new, more efficient ways of sequencing genes a top research priority. One promising technique involves reading DNA bases using changes in electrical ... full story

Dec. 4, 2012 — Using a handful of inexpensive components -- including an off-the-shelf computer webcam and a small diffraction grating, a device for splitting and diffracting light into several beams -- researchers ... full story

Oct. 6, 2011 — Biological nanopores are proteins of only a few nanometers in diameter that form tiny water-filled canals. They have proven to be promising tools in the field of nanobiotechnology. Researchers in ... full story

June 24, 2010 — Scientists have moved a step closer to developing the means for a rapid diagnostic blood test that can scan for thousands of disease markers and other chemical indicators of ... full story

ScienceDaily features breaking news and videos about the latest discoveries in health, technology, the environment, and more -- from major news services and leading universities, scientific journals, and research organizations.